Stepwise JTL-to-Odoo Migration

I am ready to leave JTL behind and would like to start by moving the smallest of my five JTL-Shop storefronts— https://meteobridge.shop/ —into Odoo so I can gain hands-on experience before tackling SwissWetter.shop and the remaining sites.

What I need from you in this pilot phase:
• Fresh Odoo installation (self-hosted or SaaS—please advise)
• Product import for Meteobridge: descriptions, images, prices, and live stock levels
• Full Payrexx payment interface set-up so I can accept cards, bank transfers, wallets, etc. through one gateway
• Shipping cost rules for Swiss Post and any future carriers
• Swiss QR-compliant invoice template plus matching quote and packing-slip layouts
• Integration (or viable alternative) for Elfsight Message to post announcements and surface Google reviews in the storefront

Once this store is running smoothly I will evaluate whether to migrate the remaining shops step by step or all at once, so your input on the pros, cons, effort, and cost difference is welcome.

Please outline:
1. A fixed-price or milestone plan for the above deliverables
2. An estimate for extending the same work to the other four shops later
3. Any optional modules or hosting considerations I should factor in

Clear documentation and a short hand-off call at the end will complete the job. Looking forward to your approach and timeline.